tools: add performance-log-deduce.py

... which statistically deduces the correct thread states based on
backtrace address frequency, fixing local inaccuracies.

(cherry picked from commit 7e186f3e5d)

tools/Makefile.am

@@ -104,5 +104,6 @@ EXTRA_DIST = \
 	gimp-mkenums			\
 	gimppath2svg.py			\
 	invert-svg.c			\
+	performance-log-deduce.py	\
 	performance-log-expand.py	\
 	performance-log-resolve.py

tools/performance-log-deduce.py

@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+
+"""
+performance-log-deduce.py -- Deduce GIMP performance log thread state
+Copyright (C) 2018  Ell
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+
+Usage: performance-log-deduce.py < infile > outfile
+"""
+
+DEDUCE_MIN_N_OCCURRENCES = 10
+DEDUCE_MIN_PERCENTAGE    = 0.75
+
+from xml.etree import ElementTree
+import sys
+
+empty_element = ElementTree.Element ("")
+
+# Read performance log from STDIN
+log = ElementTree.fromstring (sys.stdin.buffer.read ())
+
+# Construct state histogram
+address_states = {}
+
+for sample in (log.find ("samples") or empty_element).iterfind ("sample"):
+    threads = (sample.find ("backtrace") or empty_element).iterfind ("thread")
+
+    for thread in threads:
+        running = int (thread.get ("running"))
+
+        frame = thread.find ("frame")
+
+        if frame is not None:
+            address = frame.get ("address")
+
+            states = address_states.setdefault (address, [0, 0])
+
+            states[running] += 1
+
+# Find maximal states
+for address, states in list (address_states.items ()):
+    n = sum (states)
+
+    if n >= DEDUCE_MIN_N_OCCURRENCES:
+        state = 0
+        m     = states[0]
+
+        for i in range (1, len (states)):
+            if states[i] > m:
+                state = i
+                m     = states[i]
+
+        percentage = m / n
+
+        if percentage >= DEDUCE_MIN_PERCENTAGE:
+            address_states[address] = state
+        else:
+            del address_states[address]
+    else:
+        del address_states[address]
+
+# Replace thread states
+for sample in (log.find ("samples") or empty_element).iterfind ("sample"):
+    threads = (sample.find ("backtrace") or empty_element).iterfind ("thread")
+
+    for thread in threads:
+        frame = thread.find ("frame")
+
+        if frame is not None:
+            address = frame.get ("address")
+
+            running = address_states.get (address, None)
+
+            if running is not None:
+                thread.set ("running", str (running))
+
+# Write performance log to STDOUT
+sys.stdout.buffer.write (ElementTree.tostring (log))